Iridium is a modern Fabric optimization mod for Minecraft 1.21.1, designed to complement Sodium and Lithium by covering optimizations they do not include \u2014 entity and particle culling, block-entity culling, server-side throttles for hoppers, explosions, villager AI, projectiles, and dynamic FPS when the game window is unfocused.<\/p>\n
Iridium is a **companion** to Sodium and Lithium, not a replacement. Conflicting rendering mixins auto-disable at load time when Sodium is detected \u2014 and beyond Sodium, Iridium also detects **EntityCulling, MoreCulling, ImmediatelyFast and Dynamic FPS**: overlapping features automatically yield so there is no double-work or stutter from duplicate hooks.<\/p>\n
It works on both client and dedicated server. Each feature set no-ops when the environment doesn’t apply.<\/p>\n
## Performance<\/p>\n
Tested on Minecraft 1.21.1 with **Sodium + Lithium** as the baseline (the realistic starting point for any optimization-focused player). Identical scene, with many entities, particles, and block entities visible.<\/p>\n
| Setup | Avg FPS | 1% low | 0.2% low |
\n|——————————–|———-:|———-:|———:|
\n| Sodium + Lithium | 454.7 | 133.6 | 80.4 |
\n| **Sodium + Lithium + Iridium** | **499.0** | **139.7** | **89.8** |<\/p>\n
**+9.7% avg FPS \u00b7 +4.6% 1% low \u00b7 +11.7% 0.2% low**<\/p>\n
The largest gain is in the **0.2% low percentile** \u2014 the worst frames. Iridium’s main contribution is smoothing stutter in scenes with many entities, particles, and block entities, not raising an already-high average ceiling.<\/p>\n
> **Note:** Performance varies depending on hardware, software, and the scene being rendered. The numbers above come from our internal benchmark on the following configuration:
\n>
\n> **Hardware:** Intel Core i7-10700, NVIDIA RTX 5060, 32 GB DDR4-2933, Windows 11
\n> **Software:** Java 21, Fabric Loader 0.15.11, Sodium 0.6.x, Lithium latest
\n>
\n> Reproductions and counter-tests are welcomed \u2014 open an issue with your scene and your numbers.<\/p>\n
## \u2728 What Iridium does<\/p>\n
### Client-side (rendering)<\/p>\n
– **Entity Culling** \u2014 skips entities outside the camera frustum.
\n– **Particle Culling + Cap** \u2014 frustum-culls particles and caps active counts (separate cap for fireworks).
\n– **Block Entity Culling** \u2014 chests, furnaces, beacons, shulkers outside the frustum are skipped.
\n– **Animation Culling** \u2014 skips client-side animation steps for off-screen entities.
\n– **Beacon Beam Culling** \u2014 skips the beacon beam when its column is outside the frustum.
\n– **Held Item Culling** \u2014 skips item-in-hand render for off-screen mobs.
\n– **Nametag Cache** \u2014 caches rendered nametag text between frames; invalidated on change.
\n– **Map Texture Cache** \u2014 skips map texture re-upload when map data hasn’t changed.
\n– **Dynamic FPS** \u2014 drops frame rate drastically when the window is minimized or unfocused (~90% CPU\/GPU saved on Alt-Tab).<\/p>\n
### Server-side (tick)<\/p>\n
– **Hopper Throttle** \u2014 idle hoppers tick less frequently (configurable).
\n– **Explosion Ray Cache** \u2014 caches raycasts for simultaneous nearby explosions.
\n– **Random Tick Throttle** \u2014 skips random block ticks in chunks with no nearby player.
\n– **Item Entity Merge Throttle** \u2014 merge scans run every N ticks instead of every tick.
\n– **Villager AI Throttle** \u2014 reduces sensor\/brain frequency when no player is within range.
\n– **Fire Spread Throttle** \u2014 slows fire propagation in chunks with no nearby player.
\n– **Projectile Tick Throttle** \u2014 far projectiles tick 1-in-3, with a short-lookahead raycast guard so hit detection stays intact.<\/p>\n
### Quality of life<\/p>\n
– In-game config screen (ModMenu integration).
\n– Defaults tuned for maximum performance out of the box; every feature individually toggleable.
\n– Debug overlay showing culled entities, particles, hoppers and estimated savings (bind hotkey in Controls).
\n– Optional toggle hotkeys for Entity Culling, Particle Culling and Dynamic FPS.
\n– `\/iridium reload` command reloads `config\/iridium.json` without restart.<\/p>\n
## \ud83c\udfa8 Visual quality<\/p>\n
Iridium never reduces visual quality to gain FPS. No distance-based culling, no adaptive LOD, no “drop quality when FPS is low” tricks. Only geometry outside the camera frustum \u2014 which by definition you can’t see \u2014 is skipped. Server-side throttles only activate when no player is in range to observe the difference.<\/p>\n
This rule is enforced throughout the codebase and is not a config option you can turn off.<\/p>\n
## \ud83d\uddfa\ufe0f Roadmap<\/p>\n
Iridium 0.1.0 targets Minecraft 1.21.1 only. Beyond that, here’s the direction for future versions \u2014 directions, not dated promises:<\/p>\n
– **Broader Minecraft version support.** Once 0.1.0 stabilizes, Iridium will expand to the most popular long-lived Minecraft releases using Stonecutter so a single source tree can produce builds for multiple MC versions. Planned targets: **1.21.4** (Winter Drop) first as a pilot, then **1.20.1** (the version still dominant in large modpack ecosystems like Create and Cobblemon). Short-lived minors (1.21.2 \/ 1.21.3) will likely be skipped.
\n– **New optimization gaps.** Features are added based on measured wins, not hype. The design philosophy stays the same: fill specific gaps left by Sodium and Lithium, never reduce visual quality to gain FPS. Community suggestions via GitHub issues are welcome.
\n– **What will not change.** No network calls, no telemetry, no shading, no distance-based culling, no adaptive quality tricks. These are enforced by design, not toggles you have to turn off.<\/p>\n
Versions older than 1.20.1 are not planned \u2014 maintenance cost beyond three supported releases grows faster than the expected benefit.<\/p>\n
## \u2705 Compatibility<\/p>\n
Iridium is designed to coexist with the rest of the Fabric optimization ecosystem.<\/p>\n
| Mod | Status |
\n|——————|—————————————————————————|
\n| **Sodium** 0.6.x | Conflicting rendering mixins auto-disable at load time. All other features stay on. |
\n| **Lithium** | No conflicts. Iridium covers gaps Lithium doesn’t (hopper, villager AI, fire, projectiles). |
\n| **EntityCulling** (tr7zw) | Entity and block-entity culling auto-yield. No double-culling overhead. |
\n| **MoreCulling** | Beacon beam culling auto-yields. |
\n| **ImmediatelyFast** | Map texture cache auto-yields. |
\n| **Dynamic FPS** (juliand665) | Dynamic FPS feature auto-yields to prevent duplicate frame throttling. |
\n| **Starlight** | No conflicts. |
\n| **FerriteCore** | No conflicts. |
\n| **ModernFix** | No conflicts. |
\n| **ModMenu** | Optional. Used for the in-game config screen. |<\/p>\n
**No network calls. No telemetry. No shading.** Released under PolyForm Shield 1.0.0 \u2014 the same source-available license used by Sodium.<\/p>\n
### Need even more performance?<\/p>\n
By design, Iridium only fills specific gaps. For the best overall result we recommend installing it alongside Sodium (rendering pipeline) and Lithium (game logic). They cover the parts Iridium does not.<\/p>\n
## \ud83d\udce6 Modpack Policy<\/p>\n
You are completely free to include Iridium in any modpack \u2014 public or private, free or paid. **No credit or permission required.**<\/p>\n
The only thing the PolyForm Shield license does not allow is repackaging Iridium’s source code into a competing optimization mod. Normal modpack usage is always fine.<\/p>\n
## \ud83d\udce5 Installation<\/p>\n
1. Install Fabric Loader 0.15.11 or newer for Minecraft 1.21.1.
\n2. Drop Fabric API into your `mods\/` folder.
\n3. Drop the Iridium `.jar` into `mods\/`.
\n4. *(Recommended)* Add Sodium and Lithium for best results.
\n5. *(Optional)* Add ModMenu to get the in-game config screen.<\/p>\n
Launch the game. The config file is generated at `config\/iridium.json` on first run.<\/p>\n
## \ud83d\udc1b How to report issues<\/p>\n
Please use the issue tracker to report bugs, crashes and unexpected behavior. When opening an issue, include:<\/p>\n
– Minecraft version, Fabric Loader version, and Iridium version
\n– Other mods installed (especially other optimization mods)
\n– Crash log or `latest.log` if applicable
\n– Steps to reproduce<\/p>\n","protected":false},"excerpt":{"rendered":"
A Fabric optimization mod that complements Sodium and Lithium by covering the gaps they don’t touch \u2014 without reducing visual quality.<\/p>\n","protected":false},"featured_media":86337,"template":"","meta":{"_minecraft_slug":"iridiummod","_minecraft_project_id":"uPR4WJVc","_minecraft_author":"startred_","_minecraft_license":"LicenseRef-PolyForm-Shield-License-1.0.0","_minecraft_downloads":119,"_minecraft_follows":2,"_minecraft_client_side":"optional","_minecraft_server_side":"optional","_minecraft_storage_type":"zip","_minecraft_archive_name":"iridiummod.zip","_minecraft_size_bytes":99027,"_minecraft_version_count":1,"_minecraft_updated_at":"2026-05-16T14:17:00.541895Z","_minecraft_date_created":"2026-05-02T02:25:56.273784Z","_minecraft_date_modified":"2026-04-22T07:10:14.433334Z","_minecraft_project_url":"https:\/\/modrinth.com\/mod\/iridiummod","_minecraft_icon_attachment_id":86337,"_minecraft_imported_at":"2026-06-04T22:23:46+00:00","_minecraft_import_hash":"dc887dac343075b5de36fdcb84a5bd8e","_minecraft_versions":"","_minecraft_links":"","_minecraft_gallery":"","_minecraft_api_metadata":""},"mod_category":[97,90,92],"mod_loader":[99],"minecraft_version":[37],"class_list":["post-86336","mod","type-mod","status-publish","has-post-thumbnail","hentry","mod_category-fabric","mod_category-optimization","mod_category-utility","mod_loader-fabric","minecraft_version-1-21-1"],"yoast_head":"\n